We use a multiple-empirical Green's function method to determine source pro
perties of small (M - 0.4 to 1.3) earthquakes and P- and S-wave attenuation
at the Coso Geothermal Field, California. Source properties of a previousl
y identified set of clustered events from the Coso geothermal region are fi
rst analyzed using an empirical Green's function (EGF) method. Stress-drop
values of at least 0.5-1 MPa are inferred for all of the events; in many ca
ses, the corner frequency is outside the usable bandwidth, and the stress d
rop can only be constrained as being higher than 3 MPa. P- and S-wave stres
s-drop estimates are identical to the resolution limits of the data. These
results are indistinguishable from numerous EGF studies of M 2-5 earthquake
s, suggesting a similarity in rupture processes that extends to events that
are both tiny and induced, providing further support for Byerlee's Law. Wh
ole-path Q estimates for P and S waves are determined using the multiple-em
pirical Green's function (MEGF) method of Hough (1997), whereby spectra fro
m clusters of colocated events ata given station are inverted for a single
attenuation parameter, kappa, with source parameters constrained from EGF a
nalysis. The kappa estimates, which we infer to be resolved to within 0.01
sec or better, exhibit almost as much scatter as a function of hypocentral
distance as do values from previous single-spectrum studies for which much
higher uncertainties in individual kappa estimates are expected. The variab
ility in kappa estimates determined here therefore suggests real lateral va
riability in Q structure. Although the ray-path coverage is too sparse to y
ield a complete three-dimensional attenuation tomographic image, we invert
the inferred kappa value for three-dimensional structure using a damped lea
st-squares method, and the results do reveal significant lateral variabilit
y in Q structure. The inferred attenuation variability corresponds to the h
eat-flow variations within the geothermal region. A central lowe region cor
responds well with the central high-heat flow region; additional detailed s
tructure is also suggested.